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genirq: Revert sparse irq locking around __cpu_up() and move it to x86 for now

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Boris reported that the sparse_irq protection around __cpu_up() in the
generic code causes a regression on Xen. Xen allocates interrupts and
some more in the xen_cpu_up() function, so it deadlocks on the
sparse_irq_lock.

There is no simple fix for this and we really should have the
protection for all architectures, but for now the only solution is to
move it to x86 where actual wreckage due to the lack of protection has
been observed.

Reported-and-tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Fixes: a899418167 'hotplug: Prevent alloc/free of irq descriptors during cpu up/down'
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: xiao jin <jin.xiao@intel.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Yanmin Zhang <yanmin_zhang@linux.intel.com>
Cc: xen-devel <xen-devel@lists.xenproject.org>
This commit is contained in:
Thomas Gleixner 2015-07-14 22:03:57 +02:00
parent 20483d04ae
commit ce0d3c0a6f
2 changed files with 11 additions and 9 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

11
arch/x86/kernel/smpboot.c
View file

@ -992,8 +992,17 @@ int native_cpu_up(unsigned int cpu, struct task_struct *tidle)
common_cpu_up(cpu, tidle);
/*
* We have to walk the irq descriptors to setup the vector
* space for the cpu which comes online. Prevent irq
* alloc/free across the bringup.
*/
irq_lock_sparse();
err = do_boot_cpu(apicid, cpu, tidle);
if (err) {
irq_unlock_sparse();
pr_err("do_boot_cpu failed(%d) to wakeup CPU#%u\n", err, cpu);
return -EIO;
}
@ -1011,6 +1020,8 @@ int native_cpu_up(unsigned int cpu, struct task_struct *tidle)
touch_nmi_watchdog();
}
irq_unlock_sparse();
return 0;
}

9
kernel/cpu.c
View file

@ -527,18 +527,9 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen)
goto out_notify;
}
/*
* Some architectures have to walk the irq descriptors to
* setup the vector space for the cpu which comes online.
* Prevent irq alloc/free across the bringup.
*/
irq_lock_sparse();
/* Arch-specific enabling code. */
ret = __cpu_up(cpu, idle);
irq_unlock_sparse();
if (ret != 0)
goto out_notify;
BUG_ON(!cpu_online(cpu));